Press for pressing of fibre materials such as dried wood pulp, cellulose, etc.



20. 19 8 B. o. RCVDE ETAL 3,397,424

PRESS FOR PRESSING OF FIBRE MATERIALS SUCH AS DRIED WOOD PULP, CELLULOSE, ETC. Filed Sept. 23. 1965 2 Sheets-Sheet l 2 [1: MQQ XW Aug. 20, 1968 B. o. ROVDE ETAL 3,397,424

PRESS FOR PRESSING OF FIBRE; MATERIALS SUCH AS DRIED WOOD PULP, CELLULOSE, ETC. Filed Sept. 23. 1965 2 Sheets-Sheet 2 United States Patent O 2 Claims. for. 18-2) ABSTRACT OF THE DISCLOSURE A press for fiber material having a base and a reciprocating ram cooperating with said base. A reciprocating frame surrounds the base and when such frame is in an upper position it encloses the fiber material to be pressed. Then when the top of the frame is located even or below the top surface of the base the final compression of the material takes place with the edges thereof free from the frame. The movements of the ram and frame are synchronized to accomplish the above compressions. A horizontally movable gripping device located at the exterior of the press can therefore start the removal of the pressed sheet as soon as the final compression is ended and as soon as the ram starts its upward movement thereby resulting in a faster operation of such presses.

The invention relates to a press for pressing of fibre materials, such as dried wood pulp, cellulose etc. If such materials are pressed between a plane base and a ram without any arrangement of walls which encompass the material during the pressing, the material will be pressed out in lateral direction, with the result that the finished pressed sheet will get loose and irregular edges.

This drawback can be avoided by the material being pressed between a ram and a base, whilst it is surrounded on all sides by fixed and stiff walls which, together with the base, form a pressing chamber or press-box.

By pressing material in such a closed box difiiculties arise, however, in connection with removal of the air which is contained in the material.

These difficulties can be avoided by the method that the material is first pressed in closed box and subsequently subjected to a final pressing in an open press.

Such presses are known, comprising a ram, a base, a frame which forms the walls of the lower part of a pressbox, and a device for lateral removal of the ressed material from the press-box. The present invention relates to a press of this type and is in all essential respects characterized by the fact that the frame is devised to move up and down around the base from an upper position, wherein the inward turned faces of the frame form the walls of the press-box, to a lower position wherein it is found with its top face below or approximately flush with the top face of the base.

During the first part of the pressing operation, which may, for example, be effected with an oil pressure in the cylinder of approximately 150 kg./cm. or a surface pressure of approximately 50 kg./cm. the frame lies in raised position, so that the pressing takes place here in a closed box. Whilst the further pressing is effected up to an oil pressure of about 300 kg./cm. or a surface pressure of about 100 kg./cm. the frame is lowered in such manner that the edges of the pressed sheet are set free. According to a further feature of the invention, the press is provided with a gripping device for withdrawal of the completely pressed sheet from the press. The advantage of using such a gripping device instead of an ejector, which in other respects is a conventional device for removal of a pressed body from a press, lies in the fact that the Patented Aug. 20, 1968 gripping device can be carried forward to gripping position as soon as the frame is lowered. Thus the moving forward of the gripping device can take place simultaneously with the material being subjected to the final pressing. As soon as the pressing is finished, the gripping device can draw the pressed sheet out of the press. Thereby time is saved in comparison with use of an ejector, because this would, after it had pushed the sheet out of the press, have to be drawn back before the frame could begin its upward movement.

In the press according to the invention the movements of the ram and the frame are preferably synchronized, so that the downward movement of the frame takes place during the concluding pressing operation, whilst the upward movement of the frame takes place during the last part of the upward stroke of the ram. In this way time is saved. Likewise time is saved by the aforementioned synchronization of the movements of the gripping device and the frame. Thereby the capacity of the press is increased in comparison with earlier known constructions.

To make the invention more easily understandable it will now be described in greater detail in connection with the drawing, which shows diagrammatically a press according to an embodiment of the invention.

FIG. 1 shows in axial section a press with certain details removed and with a cooperating hydraulic system. The figure shows the individual parts in the position they occupy during pressing of the material in a closed box.

FIG. 2 shows a corresponding figure with the individual parts of the press in the position they occupy during the concluding pressing operation in open press. In this figure the hydraulic system is not shown.

FIG. 3 shows in the same way as FIGS. 1 and 2 the press with the individual parts in the position they occupy during withdrawal of a completely pressed sheet from the press.

FIG. 4 shows the frame and gripping device viewed from above.

In the drawing, 1 denotes the lower part of the walls in an upper pressing chamber. The openings and devices for arrangement of the material in the chamber are not shown. These devices can be of conventional type and do not form a part of the invention.

2 is a ram with rod 3. 4 is a hydraulic cylinder for actuating of the ram.

5 is a fixed base which rests on a foundation 6. 7 is a frame executed in a per se known way as a rigid and firmly joined unit devised to withstand great pressure in lateral direction. The frame is made with internal vertical faces which run flush with the inside of the walls 1. In the position shown in FIG. 1 the frame 7 forms a lower press-box. The frame rests on a suitable number, for instance two, piston rods 8, the lower ends of which carry pistons (not shown in the drawing) which work in hydraulic cylinders 9.

10 is a fork-shaped gripping device for withdrawal of the completely pressed sheet from the press. The device 10 is fastened to a piston rod 11 which at its other end carries a piston (not shown) which works in a hydraulic cylinder 12. 13 is a roll conveyor on which the pressed sheets, after they have been drawn out of the press by the device 10, are transported for further processing or storage. 14 shows the pressed material.

20 is a valve block devised for controlling the supply and removal of a hydraulic pressing medium to or from the respective cylinders 9, 12 and 4. The cylinders 9 are connected to the valve block 20 through the pipelines 21, 22, 23 and 24. The cylinder 4 is connected with the valve block 20 by means of the pipelines 27 and 28.

The valve block 20 is, further, through a pipe 29 connected with a source 30 for a pressing medium which serves for driving the cylinders 4, 9 and 12 with medium high pressure.

Through pipeline 31 the valve block 20 is connected with a source 32 for a high pressure medium for driving the press during the concluding pressing operation.

In the position shown in FIG. 1 the frame 7 lies in raised position. Ram 2 is moving downward and the material 14 is thereby pressed together to a disc or sheet, the circumference of the pressed disc or sheet bearing against the inner walls of the frame 7. This pressing can, as stated above, be effected at an oil pressure of approximately 150 kg./cm. equivalent to a surface pressure of about 50 kg./cm. By supply of a pressing medium through the lines 24 and 21 the cylinders now have the effect that the frame 7 is drawn down to the position shown in FIG. 2. The final pressing operation now takes place in open press with an oil pressure of about 300 kg./cm. equivalent to a surface pressure of about 100 kg./cm. The air trapped in the sheet can during this pressing escape from all sides.

At the same time as the final pressing commences there is supplied through the line 26 a pressing medium to the cylinder 12, and the device 10 is moved to the right, so that with its two arms it gets hold of the pressed sheet 14, as indicated in FIG. 2. When the final pressing is completed the gripping device will lie in position for withdrawal of the sheet. This withdrawal can therefore commence immediately after the ram 2 has commenced its upward movement. FIG. 3 shows the position immediately before the sheet is completely withdrawn from the press. After the withdrawal the sheet is dropped on to conveyor 13 and is carried off for further processing, storage and/ or packing.

As soon as the sheet is withdrawn from the press a pressing medium is supplied through pipelines 22 and 23 to the cylinders 9, and the frame 7 is again raised to the position shown in FIG. 1. After introduction of a new batch of material into the press-box, the above-mentioned working cyclus is repeated.

The valve block 20 can be controlled by means of contactors, time relays, pressure switches, limit switches etc. These relays etc. are not shown in the drawing and are not described in detail. They can be of commonly known type and form no part of the invention.

By the procedure according to the invention there is obtained, as will be understood from the above descrip- 4 1 tion, a shortening of the time required for a pressing operation. This shortening becomes possible in part because the frame can perform its downward movement whilst the ram concludes the pressing, and in part because the gripping device can draw out the pressed sheet as soon as the pressing is completed. Finally the frame can be raised to its pressing position immediately after the pressed sheet has been withdrawn from the press, and whilst the ram is finishing its upward movement.

We claim:

1. A press for pressing voluminous fibre material comprising a base, a frame surrounding said base, a ram, means for reciprocating said ram up and down against said base, means for moving said frame up and down from an upper position in which said frame encloses the material to-be pressed on said base to a lower position in which the top surface of said frame is below the top surface of said base, said means for moving said ram being synchronized with said means for moving said frame so that the material to be pressed will first be submitted to a compression by said ram when said material is enclosed I by said frame in said upper postion and thereafter to a final compression by said ram with a substantially higher pressure when said frame is in said lower position, a horizontally movable gripping device located at the exterior of said press to draw a pressed sheet from said press and means for moving said gripping device synchronized with said means for moving said ram and said frame so that said gripping device is moved forward to gripping position during said final compression and draws the pressed sheet out of said press when said ram starts its upward movement.

2. A press as set forth in claim 1 wherein said gripping device is fork shaped.

References Cited UNITED STATES PATENTS 2,336,982 12/1943 Cremer l8l6.5 1,005,706 10/1911 Hloch 25--4l 2,398,227 4/1946 Hubbert l816.5 2,685,117 8/1954 Rivers 25-103 2,718,030 9/1955 Collins et a1. l82 3,142,863 8/1964 Mazzoni 182 3,197,811 8/1965 Workman 18-2 J. HOWARD FLINT, J R., Primary Examiner. 

